The present invention relates to a method for sterilizing artificial organs and an apparatus used therefor.
In recent years, a rapid progress in artificial organs, the most typical of which is an artificial kidney, has been made and apparatuses such as the artificial lung, artificial liver using an activated charcoal adsorbent, ascites-treating apparatus, and plasma separator are put to practical use. Also, a variety of other therapeutic devices utilizing adsorbents such as adsorbing elements and adsorbing agents have been developed, as disclosed in Japanese Unexamined Patent Publication (Tokkyo Kokai) No. 75141/1982, No. 27559/1983, No. 10055/1983, No. 12656/1983 and No. 197255/1984.
Generally these artificial organs and therapeutic devices are sterilized in the final stage of manufacturing, aseptically sealed, and then provided to the users. The most common method of sterilization used in recent years is sterilization with high-pressure steam in an autoclave. Other methods involve the use of an aqueous solution of formaldehyde or ethylene oxide gas, or irradiation with gamma-rays. However. since in these latter methods the sterilant tends to remain in the product even at the time of use or to cause degradation of the housing of artificial organs, they are not preferred in practice from the safety point of view.
Also, conventional heat-sterilizing methods wherein high-pressure steam or high-temperature water is applied to artificial organs from the outside thereof, are disadvantageous in the following points. If artificial organs contain, as internal packings or fillers, packing fluids such as water, physiological saline water and an aqueous solution containing a stabilizer or other additives, all of which have large heat capacities, or solid packings (including packing or filling agents and materials) having a low thermal conductivity, it takes a long time to heat the portion of the internal packings or fillers in the vicinity of the center of the artificial organs to a prescribed sterilizing temperature or to cool it down after sterilization. Moreover, since the outer part of the artificial organs is heated to an unnecessarily high temperature or exposed to the high sterilizing temperature for an unnecessarily long period of time, there occur fatal defects such as degradation of the housing and internal packing and elution of harmful substances.
It is an object of the present invention to provide a method for sterilizing artificial organs which is free of the above-mentioned disadvantages.
Another object of the present invention is to provide a sterilizing apparatus used for practicing the method.
These and other objects of the present invention will become apparent from the description hereinafter.